Error using symengine, Too many input arguments, x= xf; fx = funfcn(x,varargin{:});

Hi,

could anyone help me with this problem?

I have this code:

a = 1;
b = 1;
c = 1;
d = 1;
e = 1;
f = 1;

func = @(x)(a.*x.^2 + b.*x + c)./(d.*x.^2 + e.*x + f);
syms y;
f_sym = (a.*y.^2 + b.*y + c) ./ (d.*y.^2 + e.*y + f);
df(y) = diff(f_sym, 2);
formulation = matlabFunction(formula(df));
minbnd = fminbnd(formulation, 0, 3);

And I get this error:

Error using symengine>@()0.0
Too many input arguments.
---
Error in fminbnd (line 232)
x= xf; fx = funfcn(x,varargin{:});
---
Error in Project (line 128)
    minbnd = fminbnd(formulation, 0, 3);

Thanks for your help :)

Answer 1

[Walter Roberson]

with those constants, f_sym is (y*y + y + 1)/(y*y+y+1) which is 1 except at 0. derivative of 1 is 0... with no symbolic variables.

When you matlabFunction a constant expression and do not use the 'vars' option then it looks and sees no symbolic variables, and builds a function that accepts no parameters.

You should use 'vars', y for matlabFunction to get @(y)0.0 generated. That will not have an interesting minimum but it will not crash.

[Viktor Puchý]

Hi,

how would you code it?

Thanks

[Walter Roberson]

formulation = matlabFunction(df, 'vars', y);

Remember that in context this is going to create a function that accepts a parameter and ignores it and returns a scalar 0.